Recoiling barrel-receiver assembly



Nov. 26, 1963 R. L. BROWN ETAL 3,111,883

RECOILING BARREL-RECEIVER ASSEMBLY Filed June 13, 1962 FIG-2 FIG-l INVENTORSI a I RICHARD L. BROWN l BY GEORGE DMITRIEFF ATTORNEY United States Patent Oflice 3,1 1 1,883 Patented Nov. '26, 1963 3,111,883 RECOILING BARREL-RECEIVER ASSEMBLY Richard L. Brown, Branford, and- George Dmitrieif, Bethany, Cnn., assignors to 01in Mathieson Chemical Corporation, a corporation of Virginia Filed June 13, 1962, Ser. No. 202,264 Claims. (Cl. 89-165) This invention relates to a shoulder fired firearm of the straight blowback type in which the barrel and the firing mechanism, including the receiver, bolt assembly, and magazine, are mounted for recoiling movement against a return spring in a frame which is held by the shooter.

The purpose of this arrangement is to control the dispersion of a burst, having a predetermined number of rounds.

In conventional weapons (even with a straight stock), a moment around the shoulder is created during firing. This moment tends to raise the muzzle of the weapon, so that the second and consecutive shots in a burst are fired with a different point of aim. This shifting of the muzzle causes the known stitching pattern of short burs-ts from full automatic weapons.

A weapon in which the firing mechanism and barrel assembly recoil within a frame held by the shooter during the burst, will tend to reduce dispersion for following reasons:

(a) The barrel, bolt, and receiver assemblies Will recoil during the firing, but being symmetrical about the bore and not rigidly fastened to the frame held by the shooter, cannot exert a moment force on the shoulder.

(b),The recoiling receiver compresses a return spring which transmits a force to the shoulder. The magnitude and rate of application of this spring force is so low that it has no effect on the shooters hold.

(0) Thus, as long as the receiver can recoil freely within the frame held by the shooter, the second and consecutive shots will all be aimed on the same point as the first shot.

(d) This dispersion of a burst fired in this manner will be the natural random dispersion, equivalent to that fired by single shots.

' It is thus an object of this invention to provide a shoulder fired firearm, capable of firing bursts having a predetermined number of rounds with a minimum dispersion between successive rounds.

It is a further object of this invention to provide a shoulder fired firearm in which the firing mechanism, including the receiver, bolt assembly, and the barrel, is slidably mounted in a rigid frame held by the shooter.

It is a further object of this invention to provide a shoulder fired firearm in which the firing mechanism is mounted for sliding movement in a rigid frame and recoils against a spring to eliminate any moment [forces tending to raise the gun as it is fired, and thus eliminate a pattern of dispersion between successive rounds as they are fired.

These and other objects and advantages will become more readily apparent from the following description and drawings in which:

FIGURE 1 is a sectional side view showing the oper ating mechanism of the firearm of this invention.

FIGURE 2 is a top plan view showing the firearm of this invention.

FIGURE 3 is a perspective view of the bolt assembly partly in section to show the ejector and extractor mechanism.

The firearm of this invention comprises a hollow frame, generally indicated 1, having a butt plate 2 secured to one end thereof. Hollow frame 1 has a slot 3 in the top to accommodate longitudinal movement of a magazine generally indicated 4; and a slot 5 in the bottom to accommodate the longitudinal movement of an L-shaped striker 6, which is carried by a bolt generally indicated 7.

A barrel 8 having a chamber 9 to accommodate a cartridge is mounted in the forward end of a receiver generally indicated 12. Barrel 8 has a barrel extension 10 secured thereto. A cap 11 is rigidly secured to one end of the hollow frame 1 and engages barrel extension 10 to limit the movement of barrel 8 and receiver '12 in one direction, relative to the hollow frame 1.

Receiver 12 is mounted for longitudinal sliding movement in hollow frame 1 and has a generally rectangular clip holder '13 extending upwardly through the opening 3 in frame 1. Clip holder 13 is adapted to receive and hold magazine clip 4 referred to above. Magazine clip 4 is provided with a spring 14 and a follower 14A in a conventional manner. The receiver 12 has an elongated opening 15 in the bottom wall to accommodate a downwardly extending leg 16 of L-shaped striker 6. The forward end of receiver 12 mounts barrel 8 as noted above and abuts cap 11. A plug 17 is rigidly secured to the other end of the receiver and mounts a bolt buffer 18. The bolt buffer 18 is screw-threadedly secured to the plug 17 and extends inwardly toward the forward end of the receiver.

Bolt 7 is slidably mounted in the receiver and has a forward end wall 19' abutting the chamber 9 to seal the chamber during firing of a cartridge, positioned therein. The opposite end of the bolt 7 terminates in a hollow sleeve 20. Hollow sleeve 20 accommodates and supports one end of a spring 21, which is interposed between bolt 7 and the receiver 12. Spring 21 also engages the leg 16 of striker 6, and biases the striker 6 toward chamber 9. Striker 6 is generally L-shaped as noted above with leg 1-6 extending downwardly through slot 15 in receiver 12 and slot 5 in frame 1.

Bolt buffer 18 limits the rearward sliding movement of bolt 7 relative to receiver 12. Bolt buffer 18 also actuates an ejector 22 carried by bolt 7. The ejector 22 is slidably mounted in bolt 7 and is biased rearwardly by spring 23 (note FIG. 3). As bolt 7 moves rearwardly, the buffer 18 engages ejector 22 and moves it forward relative to the bolt. This movement of the ejector pin is effective to turn a cartridge being held by an extractor 24 (also carried by bolt 7) outwardly out of engagement with the extractor and through an ejection slot (not shown) in the side wall of rigid frame 1.

A second buffer 25 is screw-threadedly engaged in a plug 26 rigidly secured to the rear of frame 1. A spring 27 is interposed between the receiver 12 and plug 26. Spring 27 is effective to urge the receiver, the barrel, and the bolt toward their normal position in the forward part of frame 1. During firing of the gun, the firing mechanism (including the receiver, bolt, and barrel) recoils against the force of spring 27 and compresses the spring which absorbs the recoiling forces of the gun. Buffer 25 is positioned in the frame 1 to limit the maximum extent to which the receiver can recoil while firing a burst containing a predetermined number of rounds.

A trigger housing generally indicated 28 is rigidly mounted intermediate the ends of frame 1. A trigger 29 is pivotally mounted in trigger housing 28, by means of a pin 30. A spring 31 is mounted on the pin 30 and engages trigger 29 to bias the trigger in a counterclockwise direction about pin 30. A sear 32 is mounted in the trigger housing by means of a pivot pin 33. Sear 32 has a radially extending arm 34 adapted to engage the downwardly extending leg 16 of the striker 6. Sear 32 has a second radially extending arm 35, which is adapted to be engaged by an actuating rod 36. A spring 37 is mounted on the pivot pin 33, and biases the sear 32 in a clockwise a,111,saa

direction about the pivot 33. Actuating rod 36 has one end pivotally secured to the trigger 29 by a pivot pin 38. The other end of the actuating rod 36 engages arm 35 of the sear 32. Pivotal movement of the trigger 29 about its pivot 30 is effective to move the actuating rod 36 axially toward the sear so that the sear is rotated in a counterclockwise direction against the force of spring 37 and out of engagement with striker 6. A cocking handle '39 is rigidly affixed to the bolt 7 and projects outwardly beyond the frame 1 through slots (not shown) in the receiver and the frame.

The operation of the firearm of this invention will now be described.

A predetermined number of rounds is loaded into the magazine 41. The bolt is manually moved rearwardly by means of the cocking handle 39 until the end wall 19 of the bolt clears the magazine 4 and allows a cartridge to project downwardly into the path of the bolt. The cocking handle is then released and the bolt is spring urged forward toward the chamber 9, by means of the spring 21. As the bolt moves toward the chamber, the first cartridge is stripped from the magazine 4 by the bolt and moved into the chamber 9. Bolt 7 seals the chamber 9 and extractor 24'engages the rim of the cartridge. The leg 16 of the striker 6 is engaged by arm 34 of the sear 32 so that the forward movement of the striker 6 is stopped. Spring 21 which is in engagement with the striker 6 urges the striker toward the cartridge in chamber 9. Upon squeezing the trigger 29, the sear 32 is rotated by means of a rod 36 out of engagement with the striker 6. The striker 6 moves forward under the force of spring 21 and fires the cartridge. The blow-back action of the case accelerates the bolt rearwardly. The bolt extracts the case by means of extractor 24. Reaching the end of its travel, the bolt impacts on buffer 18 which actuates the ejector pin 22 and ejects the case through an opening in the side of the frame. Buffer 18 absorbs the energy of the bolt and then returns a portion of it back to the bolt while simultaneously accelerating the receiver towards the rear of the rigid frame 1. The forward moving bolt strips the next round from the magazine, chambers, and fires it. At the very end of the chambering, the bolt impacts on the front portion of the barrel. This impact decelerates and/ or almost stops the rearward travel of the receiver. After the second cartridge is fired, the cycle is again repeated. During the burst firing, the receiver continues recoiling under the added impulses from the bolt rear impact. The receiver, while traveling rearwardly relative to the frame 1, compresses spring 27. The magnitude and spring rate of the spring 27 are so low that this spring force has no effect on the shooters hold. The energy stored in the spring will be used to return the receiver forward to its initial position, after completion of the burst.

This application describes in detail the structure and operation of the particular embodiment illustrated in the drawings. It is anticipated, however, that a variety of modifications and design changes may be devised in the disclosed embodiment of the invention without departing fromthe spirit and scope of the invention.

What is claimed is:

1. A shoulder-fired firearm comprising a hollow frame, a butt plate and a trigger housing rigidly secured to said frame, a firing mechanism mounted in said frame for continuous rearward movement relative to the frame as a burst including a predetermined number of rounds is fired, said firing mechanism including a receiver slidably mounted within said frame, a barrel rigidly secured to one end of said receiver and moveable therewith, a chamber in said barrel opening into said receiver, a bolt assembly including extractor means and ejector means slidably l mounted in said receiver for reciprocal movement from a forward firing position sealing said chamber to a rearward ejecting position, a spring loaded striker carried by said bolt assembly operative to fire a cartridge when said bolt assembly is in said firing position, spring means mounted between said bolt assembly and the other end of said receiver biasing said bolt assembly toward said firing position, sear means mounted in said trigger housing engageable with said spring loaded striker only when said bolt assembly and said receiver are located in their forwardmost positions, .said sear means being operative while engaging said spring loaded striker to prevent said spring loaded striker from firing the first round in said burst, trigger means mounted in said trigger housing operative to release said sear means from engagement with said spring loaded striker to fire said first round, said firing mechanism being operative to automatically fire the remaining rounds in said burst while continuously moving rearwardly relative to said frame, and spring means mounted in said frame between the receiver and the butt plate operable to return said firing mechanism to its initial position only after said burst has been fired.

2. The firearm of claim 1 including a magazine mounted in said receiver and movable therewith, said magazine being operative to supply a predetermined number of rounds into said chamber as a burst is fired.

3. The firearm of claim 1 including buffer means mounted between said bolt assembly and said receiver to limit the rearward movement of said bolt assembly relative to said receiver, said ejector means having a portion engageable with said buffer means to actuate said ejector means as the bolt assembly engages said buffer means.

4. The firearm of claim 3 in which a buffer is mounted in said hollow frame to limit the rearward movement of said receiver.

5. A shoulder-fired firearm comprising a hollow frame, a butt plate secured to one end of said frame, a trigger housing secured to said frame intermediate the ends of said frame, a receiver slidably mounted in said frame for continuous rearward movement relative to said frame as a burst containing a predetermined number of rounds is fired, spring means interposed between said butt plate and one end of said receiver to return said receiver to its forward position after said burst has been fired, a barrel including a cartridge chamber opening into said receiver secured to the other end of said receiver and movable therewith, means mounted on said frame limiting the forward movement of said barrel and receiver relative to said frame, breech bolt means slidably mounted in said receiver for reciprocal movement from a forward firing position sealing the chamber to a rearward ejecting position, spring-loaded firing means carried by said breech bolt means, sear means mounted in said trigger housing engageable with said firing means when said receiver and breech bolt means are in their forward positions operative to prevent said firing means from firing the first round in said burst, trigger means mounted in said trigger housing operative to release saidv sear means from engagement with said firing means to fire said first round, and spring means mounted between said receiver and said breech bolt means normally biasing said breech bolt toward said firing position, said barrel, receiver, breech bolt means, and firing means being operative to automatically fire the remaining rounds in said burst while continuing to move rearwardly relative to said frame.

References Cited in the file of this patent UNITED STATES PATENTS 454,993 Catlin June 30, 1891 

1. A SHOULDER-FIRED FIREARM COMPRISING A HOLLOW FRAME, A BUTT PLATE AND A TRIGGER HOUSING RIGIDLY SECURED TO SAID FRAME, A FIRING MECHANISM MOUNTED IN SAID FRAME FOR CONTINUOUS REARWARD MOVEMENT RELATIVE TO THE FRAME AS A BURST INCLUDING A PREDETERMINED NUMBER OF ROUNDS IS FIRED, SAID FIRING MECHANISM INCLUDING A RECEIVER SLIDABLY MOUNTED WITHIN SAID FRAME, A BARREL RIGIDLY SECURED TO ONE END OF SAID RECEIVER AND MOVEABLE THEREWITH, A CHAMBER IN SAID BARREL OPENING INTO SAID RECEIVER, A BOLT ASSEMBLY INCLUDING EXTRACTOR MEANS AND EJECTOR MEANS SLIDABLY MOUNTED IN SAID RECEIVER FOR RECIPROCAL MOVEMENT FROM A FORWARD FIRING POSITION SEALING SAID CHAMBER TO A REARWARD EJECTING POSITION, A SPRING LOADED STRIKER CARRIED BY SAID BOLT ASSEMBLY OPERATIVE TO FIRE A CARTRIDGE WHEN SAID BOLT ASSEMBLY IS IN SAID FIRING POSITION, SPRING MEANS MOUNTED BETWEEN SAID BOLT ASSEMBLY AND THE OTHER END OF SAID RECEIVER BIASING SAID BOLT ASSEMBLY TOWARD SAID FIRING POSITION, SEAR MEANS MOUNTED IN SAID TRIGGER HOUSING ENGAGEABLE WITH SAID SPRING LOADED STRIKER ONLY WHEN SAID BOLT ASSEMBLY AND SAID RECEIVER ARE LOCATED IN THEIR FORWARDMOST POSITIONS, SAID SEAR MEANS BEING OPERATIVE WHILE ENGAGING SAID SPRING LOADED STRIKER TO PREVENT SAID SPRING LOADED STRIKER FROM FIRING THE FIRST ROUND IN SAID BURST, TRIGGER MEANS MOUNTED IN SAID TRIGGER HOUSING OPERATIVE TO RELEASE SAID SEAR MEANS FROM ENGAGEMENT WITH SAID SPRING LOADED STRIKER TO FIRE SAID FIRST ROUND, SAID FIRING MECHANISM BEING OPERATIVE TO AUTOMATICALLY FIRE THE REMAINING ROUNDS IN SAID BURST WHILE CONTINUOUSLY MOVING REARWARDLY RELATIVE TO SAID FRAME, AND SPRING MEANS MOUNTED IN SAID FRAME BETWEEN THE RECEIVER AND THE BUTT PLATE OPERABLE TO RETURN SAID FIRING MECHANISM TO ITS INITIAL POSITION ONLY AFTER SAID BURST HAS BEEN FIRED. 